China has achieved significant progress in the manufacturing of Hydraulic Turbine and auxiliary machinery. The whole industry is thriving and full of vitality. According to the working principle, the hydraulic turbine is divided into two categories: impulse turbine and reaction turbine, and the tubular turbine is included as one of the four types of the reaction turbine.
The water flow between the guide vane and runner of the tubular turbine basically has no changes in direction. The straight conical pipe is adopted, so the outlet water does not need to take turns in the draft tube. That is the reason why it is highly efficient, with outstanding flow capacity and high specific speed. It is especially applicable for the small-scale riverbed hydropower station with the water head of 3-20 meters.
This turbine, when installed in tidal hydropower station, will also make two-way power generation. There are many structure types for the tubular turbine, and the most widely used is the bulb turbine.
The generator of the bulb-type hydro-generating unit is installed in the watertight bulb body. The turbine runner may be either designed as fixed or rotating. It may be subdivided into two types: tubular and semi-tubular. The world's largest bulb turbine (the blade-rotating semi tubular) is installed in Rock Island No.2 Hydropower Station in the United States, with the head of 12.1 meters, the speed of 85.7 rpm, the runner diameter of 7.4 meters and unit output of 54 mW. It was put into operation in 1978.